In Japan, the total volume of industrial wastes and non-industrial wastes is rapidly increasing because of the economic growth, and because of the massive movement of population into urban areas. In most cases, such wastes have traditionally been reduced to one tenth in volume by incineration and then discarded by landfill. In recent years, however, there has been urgent need for the development of a method for treating waste as the capacity of landfill sites becomes extremely tight.
In order to solve such problems, the cement industry is reusing most of the industrial wastes and non-industrial wastes as cement raw materials (e.g. Patent Document 1, etc.).
However, the waste, when hugely used as a cement raw material, poses the problem that the amount of 3CaO.Al2O3 increases and thereby heightens the hydration heat of cement. Furthermore, the mortar and concrete produced using such a cement and an admixture have the problem that a mortal flow or slump decreases and a flow loss or slump loss increases.
[Patent Document 1] Japanese Patent Laid-Open No. 56-120552